How it works?
Hydrogen fuel cell cars actually run on electric engines, but the electricity comes mostly from a chemical reaction. Hydrogen and water pass through membranes in the fuel cell. The membranes extract electrons, which then charge a battery that powers the motor.
Battery charging, meanwhile, is supplemented by regenerative braking, a technology used with conventional gas/electric hybrid cars. In regenerative braking, the work involved in slowing the car generates electricity. (In a normal car, energy consumed to slow the car gets lost as heat.)
Toyota's fuel cell car, which is based on the Highlander SUV, contains four torpedo-shaped tanks that in total contain 3.5 kilograms of compressed hydrogen. The hydrogen comes out of the pump at about 500 pounds per square inch. The car gets about 60 miles per kilogram, giving the car a range of about 200 miles.
The Ford Focus, meanwhile, has a similar range but has been cranked up to reach speeds of just 80 miles per hour, a Ford representative said. The hydrogen tanks consume most of the trunk space.
Volkswagen has demonstrated a similar hydrogen fuel cell car, but like the Ford Focus it tops out at around 80 miles per hour.
BMW is also interested in hydrogen. The carmaker is experimenting with an engine that burns hydrogen directly in the combustion process. Ideally, this would lead to greater horsepower. BMW said its car will run on liquid, rather than compressed hydrogen.